Why Leisure-Time Physical Activity Is IrrelevantThursday, October 13, 2011
One of the most popular public health measures to combat the obesity epidemic is to promote leisure-time physical activity – the notion being that leisure-time activity could prevent obesity and substantially improve the health of the population.
And, there is certainly no doubt, that one may well imagine that all the joggers and fitness enthusiasts, who we see regularly partaking in leisure sports, must have a substantial impact on population health – even when, in reality, they represent a vanishingly small proportion of the ‘at-risk’ population (I have previously suggested that if all Canadian marathon runners never ran a marathon ever again, there would likely be no discernible impact on population health. No one would notice – except orthopedic surgeons and chiropractors perhaps).
Just how irrelevant leisure-time physical activity actually is for population health is nicely demonstrated in a study by Ilona Csizmadi and colleagues from Alberta Health Services’ Department of Population Health Research, just published in the International Journal of Behavioural Nutrition and Physical Activity.
Based on their analysis of domain-specific hours of activity and energy expended among 15,591 participants in the Tomorrow Project, a prospective cohort of adults followed between 2001 and 2005 in Alberta, Canada, the primary activity-related energy expenditure in all ‘very active’ women and amongst all men, except those classified as ‘inactive’, was their occupational activity.
In addition, amongst ‘inactive’ men and women in the ‘active’, ‘low active’ and ‘inactive’ groups, activity-related energy expenditure from household activity was comparable to, or exceeded that for occupational activity.
Thus, not only did leisure-time activity-related energy expenditure decrease with decreasing physical active levels, but, even amongst the most active men and women it accounted for less than 10 percent of total energy expenditure.
Also perhaps, knowing that Alberta is one of the most car-dependent of all Canadian provinces, transportation-related activity was negligible across all categories of physical activity levels and employment status.
A ‘glass-half-empty’ perspective, would suggest that ANY increase in leisure-time physical activity amongst Albertans would prove a substantial relative increase in physical activity of the population.
On the other hand, a ‘glass-half-full’ look at these findings, would suggest that the overwhelmingly vast majority of Albertans will get their physical activity at work or not at all.
The latter makes sense, as we have originally evolved the ability to be physically active primarily to hunt, gather, fight, flee and reproduce. The notion that any reasonable person would actually engage in a significant amount of ‘non-utilitarian’ (read: useless) physical activity beyond early childhood, when play (as in all species) is really only nature’s way of helping us develop physical skills needed for hunting, flighting and flighting, or in adolescence and early adulthood, where physical prowess will increase our likelihood of finding the most desirable mate, is something that physical education enthusiasts (and governments) would wish for, but nature failed to put into our genes.
Indeed, it appears that there is a vanishingly small proportion of our species, which in adulthood will ‘voluntarily’ maintain any relevant level of ‘leisure-time’ physical activity – most will simply (and sensibly?) rest till occupational duty or household chores call again.
Loyal readers may recall that I have previously described this as the “fifth natural law of weight gain“: Don’t move if you don’t have to.
This is why, I fully concur with the researchers, who conclude that:
“For the inactive portion of this population, active non-leisure activities, specifically in the transportation and occupational domains, need to be considered for inclusion in daily routines as a means of increasing population-wide activity levels. Environmental and policy changes to promote active transport and workplace initiatives could increase overall daily energy expenditure through reducing prolonged sitting time.”
The idea that ‘education’ or ‘tax-incentives’ will ever get enough of the population voluntarily engaging in a meaningful amount of leisure-time physical activity is naive at best.
When Pheidippides, ran from Marathon to Athens, he was not seeking a runner’s high or working on his personal best time – he was merely carrying news of the Persians’ defeat to the capital.
Similarly, the original purpose of the Olympics was not to improve health or prevent heart disease but to demonstrate competencies in physical skills relevant for hunting, fighting and flighting (not to mention that winning a medal would perhaps also up your dating game).
Yes, there is a small proportion of the population, who (strangely enough) continues to enjoy leisure-time physical activity well into adulthood. The vast majority, however, prefers to much rather spend their leisure time reading, playing a musical instrument, engaging in arts and crafts, or simply lying on the couch watching professional sports. This is perfectly reasonable and completely normal human behaviour.
Nature has not designed us to enthusiastically enjoy spending hours everyday on treadmills going nowhere. But, if you have to run to catch the bus as your only means to get to work, you may just quicken your step; if you do have to walk across the room (or even to the next floor) to collect your printouts, you may actually get up and do it.
That is the difference between ‘utilitarian’ and ‘non-utilitarian’ physical activity – the former you have to do – the latter you don’t.
So the question is really not how to get more people to be active during their leisure time – the real questions are how to reintroduce physical activity to the workplace and how to promote active transportation – that may prove to be a far greater challenge than getting people to eat less.
Csizmadi I, Lo Siou G, Friedenreich CM, Owen N, & Robson PJ (2011). Hours spent and energy expended in physical activity domains: Results from The Tomorrow Project cohort in Alberta, Canada. The international journal of behavioral nutrition and physical activity, 8 (1) PMID: 21985559